1. Field of Invention
This invention relates to using radio frequency (RF) technology to catalog, track, and prevent inventory shrinkage of items. More specifically, the present invention relates to an improved method of tracking, cataloging and preventing inventory shrinkage of shipping pallets and contents contained thereon in shipping centers.
2. Description of Related Art
Shipping facilities typically have a system for cataloging, packaging, securing, and shipping items. For example, a shipping facility may receive clusters of grouped items, for example, twenty boxes of item “A,” ten boxes of item “B,” and ten bags of item “C.” In the past, the items were cataloged either by hand or electronically, placed on a pallet (e.g., a wooden tray), packaged, and placed on a shipping vehicle, such as a truck, train, ship, or the like. This system is prone to errors. For example, a given company may receive over one thousand pallets a day and load over one hundred trucks. Each pallet must be directed to the right truck, at the right time, often in the right order. Within the shipping facility, there will be many different people loading different pallets onto trucks. As a result, errors happen. Errors are very costly to the shipping facility as errors result in late shipments or lost shipments.
It is highly desirable for a shipping facility to track exactly where each pallet in its system is at any given moment and into which specific shipping vehicle the pallet should be loaded. One solution is to log each item that goes onto a pallet either by hand or electronically. Logging inventory by hand has become excessively error prone and time consuming for large shipping facilities, so they have turned to electronic means for tracking inventory.
Electronic tracking of inventory offers numerous advantages. For example, electronic tracking can allow a company to track specific items on a specific pallet. Additionally, electronic tracking may automate and expedite the tracking process. It also can reduce errors and provide for real time data related to the tracking.
To accomplish electronic tracking, each item in a group is preferably electronically tagged with an RF (radio frequency) tag, preferably an RFID (radio frequency identification) tag. When activated by a transmitter or transceiver, the RFID tag identifies itself (by identifying, for example, the product and the serial number (SN) of the product within its range by transmitting a signal. A receiver listens for the RFID tag's transmission, and logs, for example, (1) the location of the tag by noting which sensor identified the tag and (2) the time the tag was activated.
For the purposes of the present invention the terms “RFID tag” and “RFID device” are used interchangeably.
Tags such as RFID tags must be within a specific distance range in order to be activated by a transmitter. That range depends on a variety of factors such as interference, strength of the original signal (i.e, the signal emitted by a transceiver), and the type of material that is tagged. The types of material upon which the tags are applied are very variable and affect results. For example, if the pallet contains metal cans, the range for the transmission is extremely limited. Generally, metallic and highly dense materials have the most adverse effect on signal transmission strength. Because of this property, locating only a single transmitter in a fixed location, as shown, for example, in FIG. 1, is typically not an effective method of accounting for all the products on the pallet. Due to this limitation, most presently existing shipping sensors include a transmitter gate, for example, as shown in FIG. 2. The gate of FIG. 2 uses a system of six transmitters and receivers. The tags are scanned when, for example, a forklift drives through the gate. This system is expensive to manufacture due to the quantity of transmitters and receivers, the cost of the gate, floor space of the gate, etc. This system is also complex to build. For example, the transmitters and receivers all need to be synchronized to work together. A less expensive, less complex, and less obtrusive system is desirable.
Numerous patents generally related to systems of the present type are known. For example, U.S. Pat. No. 5,920,287 (Belcher et al.) discloses a radio location system for precisely tracking objects by radio frequency (RF) tags. The tags randomly and repetitively emit identification signals.
U.S. Pat. No. 5,926,110 (Downs et al.) discloses programmable output devices for controlling signal levels in an RFID transponder.
U.S. Pat. No. 5,929,760 (Monahan) discloses an RFID antenna system that includes an antenna disposed proximate to an interrogation path for interrogating transponders moving along the interrogation path. The longitudinal axis of the antenna is substantially perpendicular to the interrogation path. The antenna provides an active RF interrogation zone.
U.S. Pat. No. 5,933,354 (Shimada et al.) discloses a system for controlling the physical distribution of pallets to accurately identify pallets. The system includes wireless detecting means mounted on pallets and for detecting pallet control information.
U.S. Pat. No. 5,936,527 (Isaacman et al.) discloses an apparatus and method for an RF document control system that enables the location of, for example, office files to be easily identified. A host transceiver transmits a coded RF signal at a first frequency to individually addressable transceivers located on shelves and/or drawers. Local exciters retransmit the coded RF signal at a second frequency via an antenna. A passive RFID tag, containing the same code as that transmitted by local exciter is attached to a document or file folder. When the document or file folder is in the vicinity of the exciter, the RFID tag is energized and second frequency is modulated. A computer coupled to the host transceiver enables the system to automatically and rapidly identify, down to a specific shelf or drawer, the specific location of the tagged document.
U.S. Pat. No. 5,953,234 (Singer et al.) discloses an automated storage facility that stores items on pallets. The system provides for order picking of stacked cases. The system includes a server, client personal computers, client RF terminals, etc.
U.S. Pat. No. 5,959,568 (Woolley) discloses a system for measuring distance where an object in a storage area or moving vehicle is monitored by attaching an electronic tag to the object. An electronic device detects the presence of the object by communicating with the tag while the object is in storage or is being moved by the vehicle. The tags may also determine the location of an attached object and reroute the object if it deviates from a given shipping schedule.
U.S. Pat. No. 5,963,134 (Bowers et al.) discloses an article inventory control system for articles such as books, and uses RFID tags attached to each article. An inventory database tracks all of the tagged articles and maintains circulation status information for each article. Articles are checked out of the library using a patron self-checkout system. Checked out articles are returned to the library by being deposited into an exterior smart book drop which reads the RFID tag and automatically checks the article back in.
U.S. Pat. No. 5,970,398 (Tuttle) discloses an RF antenna with current controlled sensitivity.
U.S. Pat. No. 5,971,592 (Kralj et al.) discloses an integrated reusable pallet having data collection devices. A method for controlling inventory and shipping is disclosed that allows for the tracking and control of reusable items having data storage devices. Storage and retrieval of data onto the data storage device of the reusable item is used in the method.
U.S. Pat. No. 6,032,127 (Schkolnick et al.) discloses an intelligent shopping cart that can automatically keep track of objects in the cart. The system provides the total price of the items carried to the user of the cart. The cart has a base station and an antenna.
U.S. Pat. No. 6,075,441 (Maloney) discloses a system for tracking objects such as keys. The system includes a plurality of units, each associated with an object to be tracked.
Each unit carries a memory device that stores a unique code identifying the unit and its associated object.
U.S. Pat. No. 6,081,237 (Sato et al.) discloses an antenna/mirror apparatus in which the space occupied by a low profile antenna is reduced with the internal space of a mirror case being utilized.
U.S. Pat. No. 6,097,301 (Tuttle) discloses a method of adjusting the two-way communication range of an RFID system to assist a human operator to individually handle and interrogate a plurality of tagged objects, such as suitcases, that each include an RFID tag. An RFID transceiver is mounted is mounted on the human operator.
U.S. Pat. No. 6,148,291 (Radican) discloses container and inventory monitoring methods and systems that provide detailed logistical control of containers, shipping racks, and resident and in-transit inventory. The methods and systems create and maintain accurate real time records of the location, movement and load status of containers, racks and inventory within the facility boundaries and between facilities such as factories, assembly plants, warehouses, etc.
U.S. Pat. No. 6,150,921 (Werb et al.) discloses an article tracking system for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. The tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas receive and process the response and determine the presence of the tags by position and triangulation. The cell controllers send data from the antenna to a host computer.
U.S. Pat. No. 6,154,137 (Goff et al.) discloses an identification tag that includes a magnetically-responsive element and an RF responsive element. The magnetically responsive element may function as an antenna for the radio frequency responsive element.
U.S. Des. Pat. No. 435,557 (Eisenberg et al.) discloses a design for a handheld interrogator.
U.S. Pat. No. 6,182,053 (Rauber et al.) discloses a method and apparatus for managing inventory in a warehouse with the aid of a computer. The method and apparatus is for receiving, sorting, marking, tracking, and selling inventory.
U.S. Pat. No. 6,232,870 (Garber et al.) discloses a handheld RFID device for use in connection with items that are associated with an RFID tag. Here, particular reference is made to library materials such as books, periodicals, and magnetic and optical materials.
U.S. Pat. No. 6,335,686 (Goff et al.) discloses an antenna shelf tape disclosed for use with items having RFID elements or tags associated with items of interest. Here, the antenna shelf tape includes multiple antennae, at least one of which can be selected to facilitate the interrogation of RFID elements adjacent to a selected antenna.
U.S. Pat. No. 6,496,806 (Horwitz et al.) discloses a method and system for tracking each item in a cluster of items. Each item has an associated ID. The method and system store item records. The item records include an associated item record for storing the item ID. Each item record is linked to the other item records.
All references cited herein are incorporated herein by reference in their entireties.